Ardex DPM1C One Coat Damp Proof Membrane

Substrate Preparation

Before applying ARDEX DPM 1 C, ensure that the concrete or screed substrate is hard, sound, and free from dust, laitance, dirt, and any other materials that could prevent adhesion, such as paint, lime coatings, plaster, and adhesive residues. Any existing screeds or levelling and smoothing compounds that are not moisture-resistant must also be removed. Concrete curing agents, admixtures, surface hardeners, and their residues can impair adhesion and should be thoroughly removed. Contaminated or very smooth substrates should be prepared using appropriate mechanized surface preparation equipment. After mechanical preparation, thoroughly remove dust and fines by brushing combined with effective industrial vacuum extraction. The substrate should be prepared to a depth that exposes the aggregate and provides a sound, hard surface ready for treatment. Very uneven, rough, or porous surfaces may reduce the coverage of ARDEX DPM 1 C; in such cases, pre-smoothing with ARDITEX NA is recommended.

Calcium Sulphate-Based Screeds

For calcium sulphate screeds with moisture readings greater than 75% RH, ARDEX DPM 1 C may be used if the following conditions are met:

1. The screed manufacturer confirms that their screed can receive an epoxy DPM.
2. The subfloor contains an effective damp proof membrane, ensuring that any remaining moisture is from the construction process and not rising from the ground.
3. The screed has been down for more than 28 days and has a surface tensile strength of at least 1.0 N/mm² for smoothing applications up to 6mm thick.
4. The moisture content is less than 1.5% w/w or below 90% RH.
5. There is no underfloor heating installed.
6. No timber flooring is to be bonded to the screed.

If these criteria are met, apply ARDEX DPM 1 C at a minimum thickness of 350 microns to the prepared substrate. Smooth with 3mm-6mm ARDITEX NA, which must be applied within 48 hours of applying ARDEX DPM 1 C.

Movement Joints

Any joints or cracks in the floor that are subject to movement, such as structural movement joints, must not be bridged with ARDEX DPM 1 C. These joints should be treated with a flexible, impervious jointing system and carried through to the final floor finish before applying the damp proof membrane. Non-moving cracks in the screed should be fully stitched and filled with an appropriate resin system before applying the damp proof membrane. For more details, consult the ARDEX P 10 SR datasheet.

Applications Over Underfloor Heating

For applications over underfloor heating, ensure that the cementitious levelling screed has been laid according to BS 8204 Part 1. The underfloor heating system should be commissioned as per the manufacturer’s instructions and BS 8204 Part 1. After thermal cycling and commissioning, turn off the underfloor heating system 48 hours before and after installing ARDEX DPM 1 C, the smoothing compound, and the final floor covering. Gradually re-commission the system to avoid rapid thermal shock and temperature variations.

Mixing

ARDEX DPM 1 C comes with pre-gauged resin and hardening agents in their original containers. To mix, add the hardening agent (Component B) to the resin (Component A) and thoroughly mix using a spiral mixing paddle attached to a slow-speed drill until the mixture reaches a uniform color and consistency. Ensure all resin components are fully mixed. To reduce unmixed residues, pour some of the mixed material into the Component B container, mix for 30 seconds, then pour it back into the main mix in the Component A container and continue mixing. ARDEX DPM 1 C is ready for immediate use and has a working time of 20 minutes at 20°C. This working time is shorter at higher temperatures and longer at lower temperatures. At higher temperatures, spread ARDEX DPM 1 C immediately after mixing, as the exothermic reaction will reduce working time if the material remains in the container. Apply at temperatures above 10°C. Note: Back mixing ensures no unreacted material remains and allows for the safe disposal of packaging as non-hazardous waste.

Application

Apply an even coat of the mixed ARDEX DPM 1 C using a suitable V-shaped notched trowel over the designated area (refer to the table below for guidance). While the ARDEX DPM 1 C is still wet, flatten the serration ridges with a long-handled short-pile paint roller, which should be pre-wetted with the mixed ARDEX DPM 1 C.